K&P at Clyde Forks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the K&P at Clyde Forks clear sky chart from 2005-11-06 to 2026-07-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	15% 11% 4 9% 5% 5% 5% 4 5% 6% 31%	138582
	Night	15% 12% 4 10% 6% 5% 4 3 5% 6% 30%	134081
Transparency	Day	51% 6% 11% 20% 11% 1	142088
	Night	53% 6% 11% 19% 10% 1	138664
Seeing	Day	23% 18% 31% 18% 8% 2	16544
	Night	22% 16% 31% 23% 8% 1	25679

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 17% 6% 13% 8% 8% 6% 4 5% 6% 18%	4661
	11th to 20th	Day	10% 19% 9% 15% 8% 6% 5% 3 4 4 18%	4650
	21st to end	Day	9% 16% 7% 16% 9% 8% 5% 3 4 4 18%	5523
February	1st to 10th	Day	13% 15% 5% 12% 8% 6% 5% 4 5% 5% 23%	1890
	11th to 20th	Day	11% 16% 6% 11% 7% 5% 4 3 5% 6% 27%	1843
	21st to end	Day	17% 15% 3 10% 6% 6% 5% 4 4 4 24%	1695
March	1st to 10th	Day	17% 14% 5% 11% 6% 4 4 3 4 6% 26%	4710
	11th to 20th	Day	10% 14% 4 10% 7% 5% 6% 4 6% 6% 28%	5090
	21st to end	Day	15% 13% 4 9% 4 4 3 3 3 4 37%	5810
April	1st to 10th	Day	20% 14% 4 7% 5% 4 4 4 4 5% 31%	2520
	11th to 20th	Day	21% 12% 3 6% 4 3 3 3 3 4 36%	2494
	21st to end	Day	21% 11% 3 7% 4 4 4 3 4 5% 32%	2662
May	1st to 10th	Day	20% 10% 3 8% 5% 5% 4 4 6% 6% 29%	8237
	11th to 20th	Day	14% 9% 3 8% 5% 5% 5% 4 6% 8% 33%	8221
	21st to end	Day	19% 9% 3 7% 5% 4 4 4 5% 6% 36%	9060
June	1st to 10th	Day	20% 9% 3 7% 6% 5% 4 4 5% 6% 31%	2940
	11th to 20th	Day	14% 6% 2 7% 5% 5% 5% 4 6% 8% 37%	2940
	21st to end	Day	16% 7% 2 7% 6% 6% 4 5% 6% 8% 33%	2940
July	1st to 10th	Day	13% 7% 3 7% 6% 5% 5% 4 6% 9% 34%	6500
	11th to 20th	Day	9% 5% 2 6% 5% 4 6% 4 7% 8% 42%	6430
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 7% 9% 45%	6926
August	1st to 10th	Day	15% 8% 3 7% 5% 5% 5% 4 6% 7% 36%	4375
	11th to 20th	Day	17% 7% 2 7% 4 4 5% 4 6% 8% 36%	4174
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 7% 10% 39%	4320
September	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	2400
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 47%	2400
	21st to end	Day	17% 7% 2 7% 5% 4 4 3 6% 7% 39%	2114
October	1st to 10th	Day	20% 8% 3 6% 4 5% 4 3 4 6% 36%	2000
	11th to 20th	Day	20% 11% 3 8% 5% 4 4 3 5% 7% 29%	2000
	21st to end	Day	24% 11% 4 9% 5% 4 4 3 4 4 26%	2089
November	1st to 10th	Day	14% 12% 3 8% 6% 5% 4 4 5% 6% 33%	1814
	11th to 20th	Day	15% 14% 5% 9% 6% 5% 4 3 5% 5% 28%	1680
	21st to end	Day	19% 16% 6% 10% 6% 5% 4 3 4 6% 20%	1680
December	1st to 10th	Day	19% 20% 6% 13% 7% 5% 4 3 4 5% 14%	2680
	11th to 20th	Day	15% 18% 6% 13% 6% 5% 3 3 3 4 24%	3066
	21st to end	Day	22% 17% 5% 15% 5% 3 3 3 4 3 20%	4048
January	1st to 10th	Night	13% 15% 8% 15% 8% 5% 4 3 4 5% 19%	8234
	11th to 20th	Night	10% 17% 6% 16% 9% 6% 5% 4 4 6% 17%	8235
	21st to end	Night	10% 15% 7% 12% 7% 8% 5% 4 5% 5% 21%	8641
February	1st to 10th	Night	11% 16% 6% 13% 6% 5% 5% 4 6% 6% 23%	2730
	11th to 20th	Night	12% 14% 6% 11% 6% 6% 4 3 5% 5% 28%	2663
	21st to end	Night	12% 14% 4 10% 6% 6% 5% 4 5% 5% 28%	2110
March	1st to 10th	Night	19% 15% 4 10% 6% 4 4 2 3 4 29%	5348
	11th to 20th	Night	10% 12% 4 9% 5% 6% 6% 4 7% 8% 28%	5089
	21st to end	Night	17% 11% 4 8% 5% 4 4 3 4 6% 33%	5362
April	1st to 10th	Night	20% 11% 4 8% 5% 3 3 3 5% 5% 32%	2100
	11th to 20th	Night	19% 10% 3 7% 4 4 4 3 4 5% 36%	2075
	21st to end	Night	19% 10% 4 7% 4 4 4 3 4 6% 34%	1976
May	1st to 10th	Night	19% 11% 3 8% 5% 5% 5% 4 5% 7% 27%	4660
	11th to 20th	Night	12% 8% 3 7% 5% 4 4 3 5% 7% 41%	4639
	21st to end	Night	19% 7% 3 7% 4 4 5% 4 6% 7% 35%	5114
June	1st to 10th	Night	15% 6% 3 7% 5% 5% 5% 4 7% 7% 36%	1680
	11th to 20th	Night	11% 7% 2 7% 5% 5% 4 4 5% 6% 43%	1680
	21st to end	Night	16% 7% 3 6% 5% 4 5% 3 7% 8% 36%	1680
July	1st to 10th	Night	12% 7% 3 8% 5% 5% 5% 4 6% 9% 36%	3680
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 5% 7% 46%	3640
	21st to end	Night	8% 5% 2 6% 4 5% 5% 3 5% 7% 49%	3926
August	1st to 10th	Night	11% 6% 2 7% 4 4 5% 4 6% 8% 43%	2772
	11th to 20th	Night	14% 6% 2 6% 4 4 4 3 5% 7% 44%	2875
	21st to end	Night	12% 5% 2 6% 5% 4 5% 4 6% 8% 43%	3543
September	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 6% 7% 48%	2000
	11th to 20th	Night	13% 5% 1 4 4 4 4 3 5% 6% 52%	2000
	21st to end	Night	16% 7% 2 6% 4 3 3 4 5% 6% 43%	2281
October	1st to 10th	Night	17% 9% 2 5% 4 3 4 4 5% 6% 41%	2400
	11th to 20th	Night	18% 10% 3 8% 5% 4 4 3 6% 6% 31%	2400
	21st to end	Night	21% 11% 3 8% 5% 5% 4 3 5% 7% 29%	2750
November	1st to 10th	Night	16% 12% 4 8% 4 5% 4 3 4 5% 35%	2700
	11th to 20th	Night	16% 13% 4 8% 6% 5% 5% 4 5% 6% 29%	2940
	21st to end	Night	19% 16% 5% 10% 5% 4 4 3 4 7% 23%	2940
December	1st to 10th	Night	17% 18% 5% 12% 7% 6% 5% 4 5% 5% 16%	4720
	11th to 20th	Night	20% 16% 5% 12% 6% 4 4 3 3 4 24%	5348
	21st to end	Night	24% 18% 5% 12% 6% 4 3 2 3 4 20%	7150

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	65% 8% 10% 12% 5% 1	4662
	11th to 20th	Day	69% 5% 8% 8% 9%	4680
	21st to end	Day	69% 5% 7% 10% 8% 1	5523
February	1st to 10th	Day	63% 6% 9% 16% 6% 1	1890
	11th to 20th	Day	59% 5% 11% 15% 9% 1	1852
	21st to end	Day	62% 6% 9% 11% 10% 1	1695
March	1st to 10th	Day	60% 5% 9% 12% 13% 2	4713
	11th to 20th	Day	54% 6% 15% 14% 10% 2	5090
	21st to end	Day	50% 4 6% 18% 18% 3	5810
April	1st to 10th	Day	55% 5% 8% 17% 12% 3	2520
	11th to 20th	Day	52% 5% 7% 19% 16% 2	2494
	21st to end	Day	53% 5% 8% 16% 14% 3	2662
May	1st to 10th	Day	52% 6% 9% 20% 11% 2	8249
	11th to 20th	Day	47% 8% 12% 21% 13% 1	8225
	21st to end	Day	48% 5% 10% 23% 13% 1	9061
June	1st to 10th	Day	52% 7% 9% 19% 13% 1	2940
	11th to 20th	Day	43% 8% 11% 23% 13% 2	2940
	21st to end	Day	47% 7% 13% 21% 11% 1	2940
July	1st to 10th	Day	45% 6% 14% 25% 10%	6430
	11th to 20th	Day	35% 7% 13% 28% 15%	6355
	21st to end	Day	34% 7% 13% 36% 10%	6728
August	1st to 10th	Day	46% 7% 14% 24% 10%	4361
	11th to 20th	Day	44% 8% 14% 26% 8% 1	4213
	21st to end	Day	38% 7% 15% 30% 10% 1	4320
September	1st to 10th	Day	40% 8% 13% 28% 11%	2400
	11th to 20th	Day	35% 7% 13% 30% 15%	2400
	21st to end	Day	45% 7% 14% 24% 10%	2114
October	1st to 10th	Day	47% 5% 9% 30% 8%	3260
	11th to 20th	Day	47% 5% 14% 22% 12% 1	3240
	21st to end	Day	52% 6% 16% 19% 6%	3353
November	1st to 10th	Day	50% 7% 14% 21% 7% 1	1814
	11th to 20th	Day	57% 6% 11% 15% 9% 1	1680
	21st to end	Day	65% 8% 10% 9% 7% 1	1680
December	1st to 10th	Day	73% 6% 11% 8% 2	2680
	11th to 20th	Day	65% 5% 10% 13% 7%	3066
	21st to end	Day	70% 4 7% 14% 5%	4048
January	1st to 10th	Night	67% 7% 10% 11% 5%	8234
	11th to 20th	Night	67% 6% 9% 11% 6%	8280
	21st to end	Night	63% 6% 7% 11% 12% 1	8641
February	1st to 10th	Night	60% 5% 11% 17% 6% 1	2730
	11th to 20th	Night	58% 5% 11% 18% 8% 1	2665
	21st to end	Night	56% 6% 10% 17% 10% 1	2110
March	1st to 10th	Night	60% 4 8% 15% 10% 3	5358
	11th to 20th	Night	50% 8% 17% 15% 8% 2	5090
	21st to end	Night	52% 4 9% 20% 12% 3	5362
April	1st to 10th	Night	53% 5% 9% 18% 13% 2	2100
	11th to 20th	Night	49% 5% 7% 21% 15% 1	2075
	21st to end	Night	51% 5% 7% 18% 16% 3	1976
May	1st to 10th	Night	53% 7% 9% 20% 8% 3	4666
	11th to 20th	Night	40% 7% 14% 23% 15% 2	4640
	21st to end	Night	46% 7% 12% 19% 15% 1	5115
June	1st to 10th	Night	45% 8% 11% 22% 13% 1	1680
	11th to 20th	Night	39% 7% 11% 24% 17% 2	1680
	21st to end	Night	45% 9% 14% 20% 12% 1	1680
July	1st to 10th	Night	42% 7% 16% 19% 14% 1	3640
	11th to 20th	Night	36% 6% 13% 32% 13%	3592
	21st to end	Night	34% 6% 12% 34% 14%	3809
August	1st to 10th	Night	38% 7% 15% 26% 12% 1	2762
	11th to 20th	Night	38% 7% 15% 31% 9% 1	2902
	21st to end	Night	37% 7% 16% 28% 11% 1	3543
September	1st to 10th	Night	34% 8% 14% 30% 14% 1	2000
	11th to 20th	Night	33% 6% 13% 35% 12% 1	2000
	21st to end	Night	41% 7% 12% 29% 11%	2281
October	1st to 10th	Night	38% 5% 11% 30% 15%	3920
	11th to 20th	Night	46% 6% 16% 22% 10%	3899
	21st to end	Night	49% 7% 16% 21% 8%	4436
November	1st to 10th	Night	51% 6% 14% 20% 9%	2700
	11th to 20th	Night	54% 7% 11% 18% 8% 1	2940
	21st to end	Night	62% 6% 12% 15% 4	2940
December	1st to 10th	Night	68% 6% 13% 10% 2	4720
	11th to 20th	Night	64% 5% 7% 13% 10% 1	5348
	21st to end	Night	70% 4 6% 11% 9%	7150

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	22% 22% 40% 14% 3	220
	11th to 20th	Day	32% 20% 34% 11% 3	220
	21st to end	Day	22% 25% 36% 12% 4	316
February	1st to 10th	Day	29% 26% 32% 9% 3	330
	11th to 20th	Day	30% 26% 39% 4 1	330
	21st to end	Day	32% 27% 31% 9% 1	411
March	1st to 10th	Day	26% 25% 34% 11% 3 1	540
	11th to 20th	Day	32% 20% 31% 15% 2	540
	21st to end	Day	33% 24% 28% 11% 4	594
April	1st to 10th	Day	33% 23% 29% 11% 5%	540
	11th to 20th	Day	36% 22% 20% 15% 7% 1	532
	21st to end	Day	29% 21% 33% 10% 6% 1	540
May	1st to 10th	Day	26% 19% 31% 16% 5% 2	543
	11th to 20th	Day	20% 19% 33% 20% 7% 2	567
	21st to end	Day	22% 18% 31% 18% 8% 3	617
June	1st to 10th	Day	23% 15% 34% 19% 9% 1	570
	11th to 20th	Day	17% 17% 33% 21% 10% 2	570
	21st to end	Day	20% 13% 36% 19% 11% 1	570
July	1st to 10th	Day	12% 11% 33% 31% 11% 2	565
	11th to 20th	Day	13% 14% 32% 25% 12% 3	544
	21st to end	Day	14% 10% 36% 26% 11% 3	576
August	1st to 10th	Day	15% 7% 31% 30% 13% 4	526
	11th to 20th	Day	13% 9% 29% 29% 15% 5%	519
	21st to end	Day	15% 12% 32% 23% 13% 6%	583
September	1st to 10th	Day	16% 12% 31% 23% 12% 7%	530
	11th to 20th	Day	12% 10% 24% 26% 16% 11%	530
	21st to end	Day	19% 14% 30% 20% 12% 5%	530
October	1st to 10th	Day	22% 18% 25% 20% 10% 3	530
	11th to 20th	Day	26% 23% 30% 15% 5% 1	530
	21st to end	Day	30% 18% 31% 16% 4	521
November	1st to 10th	Day	28% 20% 29% 16% 5% 1	388
	11th to 20th	Day	28% 20% 35% 11% 5% 2	220
	21st to end	Day	33% 25% 30% 8% 4	220
December	1st to 10th	Day	30% 22% 35% 10% 3	220
	11th to 20th	Day	31% 29% 30% 7% 3 1	220
	21st to end	Day	31% 24% 30% 12% 3 1	242
January	1st to 10th	Night	24% 22% 36% 16% 3	840
	11th to 20th	Night	27% 22% 29% 17% 4 1	840
	21st to end	Night	20% 18% 36% 21% 5%	924
February	1st to 10th	Night	23% 20% 36% 19% 2	840
	11th to 20th	Night	22% 21% 41% 13% 3	823
	21st to end	Night	23% 22% 33% 19% 3	692
March	1st to 10th	Night	27% 19% 33% 18% 3	840
	11th to 20th	Night	25% 22% 32% 17% 4	840
	21st to end	Night	24% 18% 32% 19% 6%	924
April	1st to 10th	Night	29% 18% 31% 19% 3	840
	11th to 20th	Night	25% 21% 29% 19% 6%	831
	21st to end	Night	24% 17% 28% 23% 7% 1	716
May	1st to 10th	Night	22% 11% 30% 26% 9% 1	420
	11th to 20th	Night	20% 10% 36% 27% 7%	414
	21st to end	Night	14% 10% 38% 28% 11%	455
June	1st to 10th	Night	15% 11% 32% 33% 9%	420
	11th to 20th	Night	13% 14% 35% 29% 9% 1	420
	21st to end	Night	20% 9% 29% 30% 12%	420
July	1st to 10th	Night	8% 9% 33% 36% 13% 1	410
	11th to 20th	Night	12% 6% 30% 41% 11% 1	398
	21st to end	Night	10% 4 31% 43% 11% 1	438
August	1st to 10th	Night	11% 6% 24% 41% 18%	506
	11th to 20th	Night	12% 4 25% 37% 19% 3	594
	21st to end	Night	14% 7% 30% 31% 16% 2	850
September	1st to 10th	Night	15% 9% 32% 27% 16% 1	800
	11th to 20th	Night	16% 6% 23% 31% 21% 4	800
	21st to end	Night	19% 12% 24% 25% 18% 2	800
October	1st to 10th	Night	21% 13% 28% 24% 13% 2	800
	11th to 20th	Night	25% 16% 32% 20% 8% 1	800
	21st to end	Night	27% 18% 28% 23% 5%	880
November	1st to 10th	Night	26% 17% 31% 20% 6%	820
	11th to 20th	Night	23% 21% 32% 15% 8% 1	840
	21st to end	Night	31% 19% 27% 18% 4	840
December	1st to 10th	Night	28% 20% 33% 16% 3	840
	11th to 20th	Night	28% 21% 30% 18% 2	840
	21st to end	Night	33% 18% 30% 16% 3	924

Page generated at 2026-07-13 03:14:49. Version ac07

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